What is type 1 diabetes?

Type 1 diabetes (insulin-dependent diabetes mellitus) is sometimes called juvenile-onset diabetes because it usually starts in childhood or adolescence, but it can begin at any age.

In type 1 diabetes, the body makes little or no insulin, resulting in higher than normal levels of glucose in the blood.

The high blood glucose levels that occur as a result of diabetes can cause a range of different symptoms. If not controlled, over time, these may cause problems and complications, such as vision loss, kidney disease, foot and leg problems, and an increased risk of stroke and heart disease.

About 100,000 Australians have type 1 diabetes (about 0.5% of all Australians). About 1 in 700 children in Australia has type 1 diabetes. By comparison about 1 million Australians are thought to have type 2 diabetes.

Apart from type 1 diabetes, there are also two other main types of diabetes:

Gestational diabetes is similar to type 2 diabetes, but only occurs in women during pregnancy. To find out more, read our information on type 2 diabetes and gestational diabetes.

Insulin — what is it and what does it do?

Insulin is a hormone that is made in the pancreas — an organ that lies behind the stomach in the abdomen. Insulin helps to move glucose (a type of sugar) from the blood into the cells of the body so that the cells can use the glucose as an energy source — during exercise for example. Insulin also helps to change any excess glucose that the body does not immediately need into a storable form of energy (called glycogen) in the liver.

Diagram of how the pancreas and insulin work in type 1 diabetes in comparison to healthy people

In people with type 1 diabetes, the pancreas makes little or no insulin. This means that glucose can’t move into the muscles or liver, and builds up in the blood. Image: Shutterstock.com

What happens in type 1 diabetes?

In people with diabetes, the body’s usual ways of controlling blood sugar (glucose) levels do not work properly, which results in high blood glucose.

When you eat food, it is digested in your stomach, which then transports any sugar (glucose) — and other nutrients that the food contains — into your blood. The glucose is used by your body as energy for a whole range of important processes, including providing your muscles with energy during exercise.

 

Normally, insulin controls the amount of glucose in the blood and keeps it at a safe and healthy level. Normal glucose levels are between 4.0 and 7.7 millimoles [mmol] per litre [L].

Insulin helps glucose to enter the body’s cells and is also involved in storing excess glucose in the liver and in the fatty (adipose) tissues of the body. It is produced by the pancreas when blood glucose levels rise — for example after a meal.

In type 1 diabetes, the pancreas makes little or no insulin to regulate blood glucose correctly, resulting in above normal blood glucose levels — of more than 8 mmol of glucose per litre of blood.

References
  • Craig ME, Twigg SM, Donaghue KC, et al for the Australian Type 1 Diabetes Guidelines Expert Advisory Group. National evidence-based clinical care guidelines for type 1 diabetes in children, adolescents and adults. Canberra: Australian Government Department of Health and Ageing, 2011. www.diabetessociety.com.au/downloads/ Type1guidelines14Nov2011.pdf (accessed 15 November 2011).
  • Type 2 diabetes: priorities and targets. NPS NEWS (www.nps.org.au/health_professionals/publications/nps_news/current/type_2_diabetes_priorities_targets)
  • Yudkin JS, Richter B, Gale EA. Intensified glucose lowering in type 2 diabetes: time for a reappraisal. Diabetologia 2010;53:2079–85.
  • Turnbull FM, Abraira C, Anderson RJ, et al. Intensive glucose control and macrovascular outcomes in type 2 diabetes. Diabetologia 2009;52:2288–98.
  • Kearney PM, Blackwell L, Collins R, et al. Efficacy of cholesterol-lowering therapy in 18,686 people with diabetes in 14 randomised trials of statins: a meta-analysis. Lancet 2008;371:117–25.
  • Law MR, Morris JK, Wald NJ. Use of blood pressure lowering drugs in the prevention of cardiovascular disease: meta-analysis of 147 randomised trials in the context of expectations from prospective epidemiological studies. BMJ 2009;338:b1665.